Chromosome banding in Amphibia. XXV. Karyotype evolution and heterochromatin characterization in Australian Mixophyes (Anura,Myobatrachidae)

The mitotic chromosomes of the Australian ground frogs Mixophyes fasciolatus and M. schevilli were analyzed by means of banding techniques and restriction endonuclease digestions. Chromosomal differentiation in these two species occurred exclusively by considerable changes in the amount of telomeric and centromeric heterochromatin, whereas the sizes and locations of interstitial heterochromatic regions, the sizes of all euchromatic segments as well as the positions of centromeres remained nearly identical during karyotype evolution. The major heterochromatic regions in the karyotypes of M. fasciolatus and M. schevilli amount to 30.2% and 20.7%, respectively. They consist of AT base pair-rich repetitive DNA sequences that are brightly labeled by AT-specific fluorochromes and display quenched fluorescence after staining with GC-specific fluorochromes. The heterochromatic regions can be differentiated by treatment of metaphase chromosomes and interphase cell nuclei with various restriction enzymes which either disclose the complete set of C-band patterns in the karyotypes of both species, or else reveal several subsets of these C-bands.     

The influence of environment and life-history traits on the distribution of genes and individuals: a comparative study of 11 rainforest trees

This study investigates patterns of genetic connectivity among 11 co-distributed tropical rainforest tree species from the genus Elaeocarpus across a biogeographic barrier, the Black Mountain Corridor (BMC) in the Australian Wet Tropics (AWT). We analysed a combination of allelic and flanking region sequence data from microsatellite markers, and evaluated the relative influence of environmental preferences and functional traits on genetic diversity and gene flow. The results indicate that only in three species geographic structuring of haplotype distribution reflects a north vs. south of the BMC pattern. Environmental factors linked with altitude were recognized as affecting genetic trends, but the selective processes operating on upland species appear to be associated with competitiveness and regeneration opportunities on poor soil types rather than climate variables alone. In contrast to previous observations within southeastern Australian rainforests, genetic differentiation in the AWT appears to be associated with small-fruited rather than large-fruited species, highlighting how external factors can influence the dispersal dimension. Overall, this study emphasizes the importance of considering functional and environmental factors when attempting generalizations on landscape-level patterns of genetic variation. Understanding how plant functional groups respond to environmental and climatic heterogeneity can help us predict responses to future change.     

Mapping Biodiversity and Setting Conservation Priorities for SE Queensland’s Rainforests Using DNA Barcoding

Australian rainforests have been fragmented due to past climatic changes and more recently landscape change as a result of clearing for agriculture and urban spread. The subtropical rainforests of South Eastern Queensland are significantly more fragmented than the tropical World Heritage listed northern rainforests and are subject to much greater human population pressures. The Australian rainforest flora is relatively taxonomically rich at the family level, but less so at the species level. Current methods to assess biodiversity based on species numbers fail to adequately capture this richness at higher taxonomic levels. We developed a DNA barcode library for the SE Queensland rainforest flora to support a methodology for biodiversity assessment that incorporates both taxonomic diversity and phylogenetic relationships. We placed our SE Queensland phylogeny based on a three marker DNA barcode within a larger international rainforest barcode library and used this to calculate phylogenetic diversity (PD). We compared phylo- diversity measures, species composition and richness and ecosystem diversity of the SE Queensland rainforest estate to identify which bio subregions contain the greatest rainforest biodiversity, subregion relationships and their level of protection. We identified areas of highest conservation priority. Diversity was not correlated with rainforest area in SE Queensland subregions but PD was correlated with both the percent of the subregion occupied by rainforest and the diversity of regional ecosystems (RE) present. The patterns of species diversity and phylogenetic diversity suggest a strong influence of historical biogeography. Some subregions contain significantly more PD than expected by chance, consistent with the concept of refugia, while others were significantly phylogenetically clustered, consistent with recent range expansions.     

Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability

The threat of anthropogenic climate change has seen a renewed focus on understanding contemporary patterns of species distribution. This is especially the case for the biota of tropical mountains, because tropical species often have particularly narrow elevational ranges and there are high levels of short-range endemism. Here we describe geographic patterns of ant diversity and distribution in the World Heritage-listed rainforests of the Australian Wet Tropics (AWT), revealing seasonal moisture stability to be an important environmental correlate of elevational patterns of species composition. We sampled ants in leaf litter, on the litter surface and on tree trunks at 26 sites from six subregions spanning five degrees of latitude and elevation ranges from 100–1,300 m. A total of 296 species from 63 genera were recorded. Species richness showed a slight peak at mid elevations, and did not vary significantly with latitude. Species composition varied substantially between subregions, and many species have highly localised distributions. There was very marked species turnover with elevation, with a particularly striking compositional disjunction between 600 m and 800 m at each subregion. This disjunction coincides with a strong environmental threshold of seasonal stability in moisture associated with cloud ‘stripping’. Our study therefore provides further support for climatic stability as a potential mechanism underlying patterns of diversity. The average height of orographic cloud layers is predicted to rise under global warming, and associated shifts in seasonal moisture stability may exacerbate biotic change caused by rising temperature alone.     

Assessing the vulnerability of an assemblage of subtropical rainforest vertebrate species to climate change in south‐east Queensland

Global climate change is a threat to ecosystems that are rich in biodiversity and endemism, such as the World Heritage‐listed subtropical rainforests of central eastern Australia. Possible effects of climate change on the biota of tropical rainforests have been studied, but subtropical rainforests have received less attention. We analysed published data for an assemblage of 38 subtropical rainforest vertebrate species in four taxonomic groups to evaluate their relative vulnerability to climate change. Focusing on endemic and/or threatened species, we considered two aspects of vulnerability: (i) resistance, defined by indicators of rarity (geographical range, habitat specificity and local abundance); and (ii) resilience, defined by indicators of a species potential to recover (reproductive output, dispersal potential and climatic niche). Our analysis indicated that frogs are most vulnerable to climate change, followed by reptiles, birds, then mammals. Many species in our assemblage are regionally endemic montane rainforest specialists with high vulnerability. Monitoring of taxa in regenerating rainforest showed that many species with high resilience traits also persisted in disturbed habitat, suggesting that they have capacity to recolonize habitats after disturbance, that is climate change‐induced events. These results will allow us to prioritize adaptation strategies for species most at risk. We conclude that to safeguard the most vulnerable amphibian, reptile and bird species against climate change, climatically stable habitats (cool refugia) that are currently without protection status need to be identified, restored and incorporated in the current reserve system. Our study provides evidence that montane subtropical rainforest deserves highest protection status as habitat for vulnerable taxa.     

Examination of ten thousand years of mitochondrial DNA diversity and population demographics in bowhead whales (Balaena mysticetus) of the Central Canadian Arctic

Mitochondrial DNA (mtDNA) sequences were analyzed from 106 bowhead whale (Balaena mysticetus) specimens dating 471 ± 44 ¹⁴C b.p. –10,290 ± 150 ¹⁴C b.p. to evaluate whether historical changes in distribution and connectivity were detectable in levels of diversity and population structuring in the Central Canadian Arctic. The species has maintained levels of mtDNA diversity over 10,000 yr comparable to other nonbottlenecked large whale species. When compared to data from the Holocene East Greenland/Spitsbergen and contemporary Bering‐Chuckchi‐Beaufort populations, differentiation was low (F_ST≤ 0.005, Φ_ST≤ 0.003) and no temporal or geographical genetic structuring was evident. A combination of analyses suggests that the population has expanded over the past 30,000 ¹⁴C yr. This genetic signature of expansion could result from population growth, admixture of multiple gene pools, or a combination of both scenarios. Despite known climatic change that altered bowhead distribution and led to isolation of populations, there is no detectable population structuring or change in genetic diversity during the Holocene. This may be due to long generation time, occasional population connectivity and a historically large global population. These characteristics warrant caution when interpreting contemporary bowhead whale DNA data, as it is unlikely that any population will be in mutation‐drift equilibrium.     

Floristic diversity in fragmented Afromontane rainforests: Altitudinal variation and conservation importance

Question: How does the floristic diversity of Afromontane rainforests change along an altitudinal gradient? What are the implications for conservation planning in these strongly fragmented forest areas that form part of the Eastern Afromontane Biodiversity Hotspot? Location: Bonga, southwestern Ethiopia. Methods: Based on evidence from other montane forests, we hypothesized that altitude has an effect on the floristic diversity of Afromontane rainforests in southwestern Ethiopia. To test this hypothesis, detailed vegetation surveys were carried out in 62 study plots located in four relatively undisturbed forest fragments situated at altitudes between 1600 m and 2300 m. Floristic diversity was evaluated using a combination of multivariate statistical analyses and diversity indices. Results: Ordination and indicator species analyses showed gradual variations in floristic diversity along the altitudinal gradient with a pronounced shift in species composition at ca. 1830 m. Upper montane forest (>1830 m) is characterized by high fern diversity and indicator species that are Afromontane endemics. Lower montane forest (<1830 m) exhibits a greater diversity of tree species and a higher abundance of the flagship species Coffea arabica. Conclusions: Our results provide crucial ecological background information concerning the montane rainforests of Ethiopia, which have been poorly studied until now. We conclude that both forest types identified during this study need to be considered for conservation because of their particular species compositions. Owing to the high degree of forest fragmentation, conservation concepts should consider a multi‐site approach with at least two protected areas at different altitudinal levels.     

MtDNA polymorphisms: evolutionary significance in adaptation and speciation of subterranean mole rats

Patterns of mtDNA diversity in subterranean mole rats of the Spalax ehrenbergi superspecies (2n = 52, 54, 58 and 60) were previously studied in the main ranges of the four chromosomal species, and specifically in the 2n = 60 species and its peripheral steppe semi-isolates and desert isolates. In the present study we correlated mtDNA diversity indices, nucleon diversity, h , and nucleotide divergence, π, with physical (climatic), biotic (parasites) and biological (genetical, morphological, physiological and behavioural) factors, showing that mtDNA diversity is structured ecogeographically and biologically. The following significant correlations of mtDNA diversity were indicated with: (i) climatic heterogeneity and unpredictability; (ii) levels of ecto- and endoparasites; and (iii) biological diversities, primarily with physiological diversity associated with the energy budget. Small steppe semi-isolates and desert isolates harbour high levels of mtDNA haplotype diversity, some novel, which may be a prerequisite for future speciation events. We conclude that the ecogeographical and biological correlates, as well as the maintenance of mtDNA polymorphisms in small isolated populations, strongly suggest that mtDNA diversity is not neutral. Diversifying natural selection appears to be an important differentiating factor of mtDNA diversity in the twin evolutionary processes of adaptive radiation and active speciation. We suggest critical experiments to substantiate our conclusions and highlight the contribution of mtDNA diversity to fitness, i.e. to the biological function of mtDNA diversity in the evolutionary process.     

EVOLUTIONARY AND BIOGEOGRAPHIC ORIGINS OF HIGH TROPICAL DIVERSITY IN OLD WORLD FROGS (RANIDAE)

Differences in species richness between regions are ultimately explained by patterns of speciation, extinction, and biogeographic dispersal. Yet, few studies have considered the role of all three processes in generating the high biodiversity of tropical regions. A recent study of a speciose group of predominately New World frogs (Hylidae) showed that their low diversity in temperate regions was associated with relatively recent colonization of these regions, rather than latitudinal differences in diversification rates (rates of speciation–extinction). Here, we perform parallel analyses on the most species-rich group of Old World frogs (Ranidae; ∼1300 species) to determine if similar processes drive the latitudinal diversity gradient. We estimate a time-calibrated phylogeny for 390 ranid species and use this phylogeny to analyze patterns of biogeography and diversification rates. As in hylids, we find a strong relationship between the timing of colonization of each region and its current diversity, with recent colonization of temperate regions from tropical regions. Diversification rates are similar in tropical and temperate clades, suggesting that neither accelerated tropical speciation rates nor greater temperate extinction rates explain high tropical diversity in this group. Instead, these results show the importance of historical biogeography in explaining high species richness in both the New World and Old World tropics.     

A striking lack of genetic diversity across the wide-ranging amphibian <Emphasis Type="Italic">Gastrophryne carolinensis</Emphasis> (Anura: Microhylidae)

We examine phylogeographic structure across a wide-ranging microhylid frog (Gastrophryne carolinensis) using both mitochondrial (mtDNA) and nuclear (AFLP) data. Species with similar ecological characteristics such as large range size, low vagility, or existence across known biogeographic barriers, often are comprised of multiple, cryptic lineages. Surprisingly, our analyses of both portions of the genome show very little phylogeographic or population genetic structure. The family Microhylidae is one of the largest families of anurans with over 60 genera and around 400 species distributed across much of the world (Americas, Asia, Africa, and Madagascar), but very few phylogeographic studies have assessed intraspecific genetic diversity across the mitochondrial and nuclear genomes. Our results suggest that G. carolinensis, one of only three species of microhylid native to the US, has experienced a severe population bottleneck with subsequent range expansion. Comparable molecular data from closely related microhylids, in addition to demographic and ecological analyses, will provide valuable insight into patterns of genetic diversity and the processes driving phylogeographic diversity in these wide-ranging frogs.     

Population Recovery following Decline in an Endangered Stream-Breeding Frog (Mixophyes fleayi) from Subtropical Australia

Amphibians have undergone dramatic declines and extinctions worldwide. Prominent among these have been the stream-breeding frogs in the rainforests of eastern Australia. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has been postulated as the primary cause of these declines. We conducted a capture-mark-recapture study over a 7-year period on the endangered Fleay’s barred frog (Mixophyes fleayi) at two independent streams (30 km apart) in order to assess the stability of these populations. This species had undergone a severe decline across its narrow geographic range. Mark-recapture modelling showed that the number of individuals increased 3–10 fold along stream transects over this period. Frog detection probabilities were frequently above 50% but declined as the populations increased. Adult survival was important to overall population persistence in light of low recruitment events, suggesting that longevity may be a key factor in this recovery. One male and female were present in the capture record for >6 years. This study provides an unambiguous example of population recovery in the presence of Bd.     

Genetic variation of an endangered Malagasy frog, <Emphasis Type="Italic">Mantella cowani</Emphasis>, and its phylogeographic relationship to the widespread <Emphasis Type="Italic">M. baroni</Emphasis>

We investigated the degree and distribution of the genetic variation, and phylogeography, of two species of Malagasy poison frogs, Mantella cowani and M. baroni. The former is critically endangered due to its restricted distribution, habitat destruction and overcollection for the pet trade. Analysis of 526 bp of mtDNA (cytochrome b) resulted in separate haplotype networks for the two species, and discovered hybridization at a single locality. The two networks confirm the status of M. baroni and M. cowani as separate evolutionary species and units for conservation. Within both mitochondrial haplotype networks, specimens from different localities shared numerous identical haplotypes, even those from the most distant sample sites of M. baroni. Most populations were characterized by high haplotype diversity and no haplotype clades exclusive to geographical regions were observed. Protection of a few large populations of these species is therefore likely to conserve much of the mtDNA genetic diversity found in the entire species. While M. baroni is widespread and occurs in many nature reserves, we recommend efficient legal protection of some M. cowani habitats to protect this species against extinction.     

Climatic oscillations triggered post-Messinian speciation of Western Palearctic brown frogs (Amphibia,Ranidae)

Oscillating glacial cycles over the past 2.4 million years are proposed to have had a major impact on the diversity of contemporary species communities. We used mitochondrial and nuclear DNA sequence data to infer phylogenetic relationships within Western Palearctic brown frogs and to test the influence of Pliocene and Pleistocene climatic changes on their evolution. We sequenced 1976bp of the mitochondrial genes 16S rRNA and cytochrome b and of the nuclear rhodopsin gene for all current species and subspecies. Based on an established allozyme clock for Western Palearctic water frogs and substitution rate constancy among water frogs and brown frogs, we calibrated a molecular clock for 1425bp of the 16S and rhodopsin genes. We applied this clock to date speciation events among brown frogs. Western Palearctic brown frogs underwent a basal post-Messinian radiation about 4 million years ago (mya) into five major clades: three monotypic lineages (Rana dalmatina, Rana latastei, Rana graeca), an Anatolian lineage, and a lineage comprising Rana italica, Rana arvalis, and all Iberian taxa. Polytypic lineages radiated further in concordance with the onset of climatic oscillations ca. 3.2, 2.0, and 1.0-0.6 mya, respectively. The dated fossil record corroborates our paleobiogeographic scenario. We conclude that drastic climatic changes followed by successive temperature oscillations "trapped" most brown frog species in their southern European glacial refugia with enough time to speciate. Substantial dispersal was only possible during extensive interglacial periods of a constant subtropical climate.     

Pleistocene climatic changes drive diversification across a tropical savanna

Spatial responses of species to past climate change depend on both intrinsic traits (climatic niche breadth, dispersal rates) and the scale of climatic fluctuations across the landscape. New capabilities in generating and analysing population genomic data, along with spatial modelling, have unleashed our capacity to infer how past climate changes have shaped populations, and by extension, complex communities. Combining these approaches, we uncover lineage diversity across four codistributed lizards from the Australian Monsoonal Tropics and explore how varying climatic tolerances interact with regional climate history to generate common vs. disparate responses to late Pleistocene change. We find more divergent spatial structuring and temporal demographic responses in the drier Kimberley region compared to the more mesic and consistently suitable Top End. We hypothesize that, in general, the effects of species’ traits on sensitivity to climate fluctuation will be more evident in climatically marginal regions. If true, this points to the need in climatically marginal areas to craft more species‐(or trait)‐specific strategies for persistence under future climate change.     

Reticulate evolution and the origins of ribosomal internal transcribed spacer diversity in apomictic Meloidogyne

Among root knot nematodes of the genus Meloidogyne, the polyploid obligate mitotic parthenogens M. arenaria, M. javanica, and M. incognita are widespread and common agricultural pests. Although these named forms are distinguishable by closely related mitochondrial DNA (mtDNA) haplotypes, detailed sequence analyses of internal transcribed spacers (ITSs) of nuclear ribosomal genes reveal extremely high diversity, even within individual nematodes. This ITS diversity is broadly structured into two very different groups that are 12%-18% divergent: one with low diversity (< 1.0%) and one with high diversity (6%-7%). In both of these groups, identical sequences can be found within individual nematodes of different mtDNA haplotypes (i.e., among species). Analysis of genetic variance indicates that more than 90% of ITS diversity can be found within an individual nematode, with small but statistically significant (5%-10%; P < 0.05) variance distributed among mtDNA lineages. The evolutionarily distinct parthenogen M. hapla shows a similar pattern of ITS diversity, with two divergent groups of ITSs within each individual. In contrast, two diploid amphimictic species have only one lineage of ITSs with low diversity (< 0.2%). The presence of divergent lineages of rDNA in the apomictic taxa is unlikely to be due to differences among pseudogenes. Instead, we suggest that the diversity of ITSs in M. arenaria, M. javanica, and M. incognita is due to hybrid origins from closely related females (as inferred from mtDNA) and combinations of more diverse paternal lineages.     

Evolution of Cryptocephalus leaf beetles related to C. sericeus (Coleoptera: Chrysomelidae) and the role of hybridization in generating species mtDNA paraphyly

Gómez‐Zurita, J., Sassi, D., Cardoso, A. & Balke, M. (2011). Evolution of Cryptocephalus leaf beetles related to C. sericeus (Coleoptera: Chrysomelidae) and the role of hybridization in generating species mtDNA paraphyly. —Zoologica Scripta, 41, 47–67. Autochthonous European insect diversity is the result of the very complex geological, geographic and climatic history of the Mediterranean area. The leaf beetle genus Cryptocephalus has over 250 species in this area. Among them stands out a group nearly endemic from this region consisting of conspicuous metallic green or blue beetles which can be found visiting yellow Asteraceae flowers in most mid‐ to high‐altitude European grasslands: the Linnaean species C. hypochaeridis, C. sericeus, and all their relatives. In all, these are 32 species forming several taxonomically complex groups across Europe. We sampled all morphological diversity in this lineage and characterized it for two mitochondrial DNA genes. The mtDNA phylogeny of this assemblage was inferred, as well as the timing of its diversification using standard mtDNA substitution rates and a hypothetical Messinian vicariant split. The origin of the group can be traced back to western continental Eurasia in the Lower Miocene. Its subsequent taxonomic splits can be linked to specific periods in the formation of Europe, with a marked trend to east–west phylogenetic divides throughout time and space, and a nearly constant rate of diversification. Only during the Pleistocene, a significant increase in diversification rate can be associated with species formation in the C. hypochaeridis and C. sericeus species complexes. Within these latter groups, most taxa show some degree of mtDNA paraphyly as a result of their recent separation and remarkably by episodes of gene flow in areas of secondary contact among recently diverged species, possibly driven by climatic change.     

Two Species with an Unusual Combination of Traits Dominate Responses of British Grasshoppers and Crickets to Environmental Change

There are large variations in the responses of species to the environmental changes of recent decades, heightening interest in whether their traits may explain inter-specific differences in range expansions and contractions. Using a long-term distributional dataset, we calculated range changes of grasshoppers and crickets in Britain between the 1980s and the 2000s and assessed whether their traits (resource use, life history, dispersal ability, geographic location) explain relative performance of different species. Our analysis showed large changes in the distributions of some species, and we found a positive relationship between three traits and range change: ranges tended to increase for habitat generalists, species that oviposit in the vegetation above ground, and for those with a southerly distribution. These findings accord well with the nature of environmental changes over this period (climatic warming; reductions in the diversity and increases in the height of vegetation). However, the trait effects applied mainly to just two species, Conocephalus discolor and Metrioptera roeselii, which had shown the greatest range increases. Once they were omitted from the analysis, trait effects were no longer statistically significant. Previous studies on these two species emphasised wing-length dimorphism as the key to their success, resulting in a high phenotypic plasticity of dispersal and evolutionary-ecological feedback at their expanding range margins. This, combined with our results, suggests that an unusual combination of traits have enabled these two species to undertake extremely rapid responses to recent environmental changes. The fact that our results are dominated by two species only became apparent through cautious testing of the results’ robustness, not through standard statistical checks. We conclude that trait-based analyses may contribute to the assessment of species responses to environmental change and provide insights into underlying mechanisms, but results need to be interpreted with caution and may have limited predictive power.     

Comparative Phylogeography of Direct-Developing Frogs (Anura: Craugastoridae: Pristimantis) in the Southern Andes of Colombia

The Andes of South America hosts perhaps the highest amphibian species diversity in the world, and a sizable component of that diversity is comprised of direct-developing frogs of the genus Pristimantis (Anura: Craugastoridae). In order to better understand the initial stages of species formation in these frogs, this study quantified local-scale spatial genetic structuring in three species of Pristimantis. DNA sequences of two mitochondrial gene fragments (16S and COI) were obtained from P. brevifrons, P. palmeri and P. jubatus at different locations in the Cordillera Occidental. We found high levels of genetic diversity in the three species, with highly structured populations (as measured by F _ST) in P. brevifrons and P. palmeri while P. jubatus showed panmixia. Large effective population sizes, inferred from the high levels of genetic diversity, were found in the three species and two highly divergent lineages were detected within P. jubatus and P. palmeri. Estimated divergence times among populations within P. brevifrons and P. palmeri coincide with the Pleistocene, perhaps due to similar responses to climatic cycling or recent geological history. Such insights have important implications for linking alpha and beta diversity, suggesting regional scale patterns may be associated with local scale processes in promoting differentiation among populations in the Andes.     

Reconciling genetic expectations from host specificity with historical population dynamics in an avian brood parasite, Horsfield's Bronze-Cuckoo Chalcites basalis of Australia

Mitochondrial DNA (mtDNA) is being used increasingly to explore the evolution of host specificity in avian brood parasites. A stable coevolutionary equilibrium between multiple phylogenetically unrelated hosts and a brood parasitic species predicts that mtDNA diversity in the parasite should be relatively deep and phylogenetically structured. Also, the different intraspecific clades resulting from parasitism to multiple sympatric hosts should themselves occur sympatrically. However, mtDNA diversity in brood parasites is as susceptible to effects of historical population dynamics as in any species. We demonstrate the relevance of these dynamics to the use of mtDNA in understanding coevolution between an Australian brood-parasite, Horsfield's Bronze-Cuckoo Chalcites basalis and its hosts, Malurus fairy-wrens and Acanthiza thornbills. Previous ecological and behavioural analyses argue that Malurus- and Acanthiza-specific host races exist in C. basalis. Yet mtDNA diversity in C. basalis is low and phylogenetically unstructured (mean sequence divergence 0.15 +/- 0.07%, range 0.00%-0.31%) and tests of mtDNA neutrality and range expansion vs. population stability (Tajima's D, Fu & Li's F* and D*, Fu's F(S), mismatch analyses) all indicate that C. basalis has expanded its range very recently, probably within the last few tens of thousands of years following climatic amelioration after a peak of aridity in the late Pleistocene. The low mtDNA diversity and its lack of phylogenetic structure in C. basalis deny the existence of evolutionarily long-term stable host races in C. basalis but not the possibility of recently evolved ones. They highlight the need for renewed behavioural and ecological study of the relationship between C. basalis and its hosts. Our findings illustrate the need to understand the evolutionary context in which a brood parasite and its hosts have evolved if mtDNA data are to be used in testing hypotheses concerning the origin and maintenance of host specificity. They also add to the growing body of work illustrating the use of mismatch analyses and Fu's F(S) in detecting range expansions.     

An Ancient Divide in a Contiguous Rainforest: Endemic Earthworms in the Australian Wet Tropics

Understanding the factors that shape current species diversity is a fundamental aim of ecology and evolutionary biology. The Australian Wet Tropics (AWT) are a system in which much is known about how the rainforests and the rainforest-dependent organisms reacted to late Pleistocene climate changes, but less is known about how events deeper in time shaped speciation and extinction in this highly endemic biota. We estimate the phylogeny of a species-rich endemic genus of earthworms (Terrisswalkerius) from the region. Using DEC and DIVA historical biogeography methods we find a strong signal of vicariance among known biogeographical sub-regions across the whole phylogeny, congruent with the phylogeography of less diverse vertebrate groups. Absolute dating estimates, in conjunction with relative ages of major biogeographic disjunctions across Australia, indicate that diversification in Terrisswalkerius dates back before the mid-Miocene shift towards aridification, into the Paleogene era of isolation of mesothermal Gondwanan Australia. For the Queensland endemic Terrisswalkerius earthworms, the AWT have acted as both a museum of biological diversity and as the setting for continuing geographically structured diversification. These results suggest that past events affecting organismal diversification can be concordant across phylogeographic to phylogenetic levels and emphasize the value of multi-scale analysis, from intra- to interspecies, for understanding the broad-scale processes that have shaped geographic diversity.